The present invention relates to methods and devices for reducing power consumption in a passive optical network (PON) while maintaining service continuity.
Fiber access networks (e.g. Ethernet PON-EPON and gigabit PON-GPON) provide continuous operation for allowing ultra-high-speed communication. During network operation, the optics are always powered on, the media access control (MAC) unit is clocked, and the MAC logic is being toggled. The power consumption varies only slightly with respect to the actual consumed bandwidth.
Reducing power consumption is fiber access networks is a growing concern due to fiber installations that use batteries for powering optical-network units (ONUs) during a power outage. Reducing the power consumption enables both a smaller and less-costly battery and a longer “battery-backup” time. Furthermore, due to concerns over global warming, improving the power consumption of electronic devices is considered to be a global demand.
In order to reduce power consumption effectively, two requirements need to be met. The first requirement is to reduce power consumption in the fiber access network by reducing activity and responsiveness. The second requirement is to maintain service availability.
In the prior art, there are known schemes for low-power operation of ONUs and optical-line terminals (OLTs). US Patent Publication No. 20060053309, incorporated by reference as if fully set forth herein, teaches an ONU with low-power sleep logic that substantially extends the life of the battery after the AC main power supply has been lost. US Patent Publication No. 20060029389, incorporated by reference as if fully set forth herein, teaches an ONU with low-power hibernation. In both prior-art references, the ONU is powered off with only a “watchdog” circuit is remaining active. Such prior-art methods cannot guarantee service continuity.
It would be desirable to have methods and devices for reducing power consumption in a PON while maintaining service continuity.